The intended objective of this research is to identify regulatory genes which affect the level and/or developmental profile of ADH in Drosophila melanogaster. Natural variants will be sought by placing chromosomes from the populations being analyzed in an isogenic background and determining ADH activity at different developmental stages. Also, possible cis-acting elements from different Adh strains will be associated with the same structural gene by recombination and their effect on ADH levels monitored. In order to detect newly induced mutations, unlinked to Adh, that lead to lack of enzymatic activity compound chromosomes will be used to generate homozygotes for the mutagenized chromosomes. Mutants will be recovered with a chemical selective. A genetic element which influences the level of ADH accumulated in adults will be mapped genetically. Also the effect of this element on ADH in individual organs and at various times in development will be investigated.